The present invention relates to catalytic amination of alkanolamines or glycols with ammonia to form diamines, polyamines, alkanolamines, and piperazine, or their derivatives by employing a catalyst composed of two active elements from the transition metal family, uniformly combined with a refractory microporous substrate. This process operates at lower temperatures and pressures than have hitherto been used.
A considerable number of methods for production of alkylamine products have been proposed and a number of them have been commercially utilized.
It is believed that two mechanisms are prominent in this process and they are: Reductive Amination and Heterogeneous Catalysis.
Reductive Amination: For ethylenediamine formation, the previous studies on ammonalysis of various alcohols is useful because alcohols such as ethanol and butanol are known to go via their corresponding aldehyde to primary, secondary and tertiary amines. Other studies have isolated the intermediate aldehyde (Pasek et al., 1972) (Baiker and Ridaz, 1977). The most direct evidence is by Bashirov (1971), who used isotope labeling to verify the mechanism.
Heterogeneous Catalysis: This is the straightforward reaction of —OH and —NH or NH2 to form secondary or cyclic amines.
Reductive amination via catalytic hydrogenation of a mixture of aldehyde or ketone and ammonia leads to a predominance of primary amine when excess ammonia is present. At least five equivalents of ammonia should be used; smaller amounts result in formation of more secondary amine.
Various catalysts are manufactured and developed for amination of amines, some of which are discussed below:
U.S. Pat. No. 4,209,424 discloses a catalyst for implementing a process for manufacturing amines from alcohols composed of an active element in the transition metals family uniformly combined with a refractory porous structure with a specific surface of between 10 m2/g and 300 m2/g and with a pore diameter less than 5000 Å. A stabilizer in the form of a sodium-based compound with a sodium content of 0.15% to 20% by weight relative to the weight of the catalyst, and a promoter in the form of a rhodium-based compound with a maximum rhodium content of 0.1% by weight relative to the weight of the catalyst, may be associated with the active metal. The catalyst and the process are applicable to the ethanolamine-ammonia reaction with a view to producing ethylenediamine, piperazine, and useful byproducts. The amination reaction is carried out at 170° C. and 260° C.
U.S. Pat. No. 4,123,462 discloses nickel-rhenium catalyst and catalytic amination of lower aliphatic alkane derivatives such as alkanemono-ols, alkanediols and alcoholamines utilizing the said nickel-rhenium catalyst. The amination reaction is carried out at 125° C. to 350° C.
U.S. Pat. No. 7,601,875 discloses a process for the preparation of ethyleneamines by reacting monoethanolamine (MEOA) with ammonia in the presence of a catalyst in a reactor and separating the resulting reaction product, which comprises reacting ethylenediamine (EDA) obtained during the separation in a separate reactor in the presence of a catalyst to give diethylenetriamine (DETA), and the resulting reaction product is passed to the separation of the reaction product resulting from reactor. The reaction is carried out at temperature of 170° C. and a pressure of 200 bar.
U.S. Pat. No. 6,534,441 discloses a nickel/rhenium catalyst composition for the reductive amination of lower aliphatic alkane derivatives.
Process for production of ethylenediamine carried out by reacting ammonia with monoethanolamine in the presence of a catalyst at 200° C. to 500° C. in an atmosphere of an inert gas (e.g., nitrogen) according to demand is disclosed in Japanese Patent No. 3511666. The catalyst is prepared by heat-treating zeolite (e.g., mordenite) in an aqueous solution of EDTA, and has a high activity and a long service life.
U.S. Pat. No. 5,410,086 discloses a method for increasing the weight ratio of diethylenetriamine to piperazine at constant ethylenediamine conversion and constant space velocity in a process in which ethylenediamine and hydrogen are maintained in the presence of a hydrogenation catalyst, which method comprises increasing the hydrogen concentration in the liquid phase in an amount sufficient to effectuate control of the weight ratio of diethylenetriamine to piperazine in said process, and the catalyst is selected from nickel (Raney nickel), cobalt, or rhodium.
A number of production methods are utilized to produce the diamine and polyamine products and various catalysts are developed for these process. These processes, while generally employed throughout the industry, suffer from serious disadvantages.
The currently used processes for producing the products such as ethylenediamine, piperazine, aminoethylethanolamine, diethylenetriamine, aminoethylpiperazine, and hydroxyethylpiperazine are cumbersome, and a balance has to be struck between conversion-per-pass of the reactor, selectivity of the large volume products, and operating conditions. Generally if one increases conversion, selectivity decreases and more small-market yet high-value products are formed.
Further, these processes utilized for production of aforesaid products are carried out under extremely high pressures (200 kg/cm2g) and temperatures (200° C.-254° C.), far above the critical pressure and temperatures of ammonia. These processes therefore are operating in the supercritical fluid region for ammonia which normally represents >80% of the volume flow to the reactor.
Therefore, there still exists a need in the art to develop a catalyst that helps in manufacturing high value product with higher selectivity, and at the same time carries out the process of amination at low temperature and pressure.
Therefore, it is an object of the present invention to provide a process of amination of alkanolamines or glycols with ammonia to form diamines, polyamines, and piperazine, or their derivatives.
Another object of this invention is to carry out the amination reaction at a pressure much lower than the critical pressure of ammonia and initiate the reaction at a temperature below the critical temperature of ammonia.
Yet another object of the present invention is to provide an amination catalyst to be employed in the process of amination of alkanolamines or glycols.
Another object of the present invention is to provide a process of amination having high yield and selectivity of diamines produced during the reaction.